Installing module to blender's python (Mac)
For some reason using cd to blender's python bin folder and then executed command was not working, but ... path to blender's bin folder with python3.7m + command executed at once worked just fine.

Do I have a &quot;pip&quot;?
I don't know if 2.80 was distributed without a pip (as mentioned above), but 2.79 and also 2.83 Mac build containes a pip ... executing ensurepip was satisfied. You can check that by right click on Blender.app icon &gt; Show Package Contents &gt; Contents &gt; Resources &gt; 2.9x &gt; python &gt; bin, drag&amp;drop bin folder into Terminal window, type python3.7m -m ensurepip and execute. In my case it looked like ...
/Users/Filip/Downloads/Blender\ 92.app/Contents/Resources/2.92/python/bin/python3.7m -m ensurepip

Upgrade &quot;pip&quot;
Terminal recommend update pip to latest version. So copy&amp;paste directory of bin folder or drag&amp;drop bin folder again  into Terminal window, type  python3.7m -m pip install --upgrade pip and execute. My example ...
/Users/Filip/Downloads/Blender\ 92.app/Contents/Resources/2.92/python/bin/python3.7m -m pip install --upgrade pip

Module installation
From what I tried, even without pip care I could just install module by command
python3.7m -m pip install + type your module name. In my case open3d module...
/Users/filip/Downloads/Blender\ 92.app/Contents/Resources/2.92/python/bin/python3.7m -m pip install open3d